This invention relates to a novel synthesis of 2,6-disubstituted benzonitriles from 2,6-disubstituted benzaldehydes.
In a conventional synthesis of 2,6-disubstituted benzonitriles from the corresponding 2,6-disubstituted benzaldehydes a two step process is involved in which the aldehyde is first converted to the corresponding oxime. The oxime is then isolated from the mixture and dried, and then the dried oxime is subjected to a dehydrating reagent such as phosphorous oxychloride.
Although frequently high yields can be achieved by the use of this process (in the case of 2,6-dichlorobenzaldehyde yields of approximately 90% of 2,6-dichlorobenzonitrile being achieved) the necessity for employing expensive equipment, the increased expenditure of man-hours and the increased time involved when a two-step process is employed renders a one-step process to be highly desirable.
However, although a one step conversion of aldehyde to nitrile has been employed for an analogous compound, the conversion of 2,4-dichlorobenzaldehyde to 2,4-dichlorobenzonitrile, as reported by J. H. Hunt Chemistry and Industry, November 18, 1961, page 1873 such as a small yield was obtained, (30%) that it would appear that the utilization of a one step conversion of the 2,6-disubstituted benzaldehyde to the 2,6-disubstituted benzonitrile would yield equally poor results.
It is an object of this invention therefore to provide a one step method of synthesis of 2,6-disubstituted benzonitriles from 2,6-disubstituted benzaldehydes in which a good yield of the 2,6-disubstituted benzonitrile is achieved.
Another object of this invention is to provide a one step method for the synthesis of 2,6-dichlorobenzonitrile, a well known herbicide from the corresponding benzaldehyde.
These and other objects of the invention will be apparent from the description that follows.